1. Field of the Invention
This invention relates to a field frame changeover mechanism for changing a viewfinder field of a camera between two different exposure modes.
2. Description of the Prior Art
Conventionally, in addition to taking full-size photos by exposing an entire frame of film when the shutter is released, cameras which can perform panorama photo-taking by covering the top and bottom portions of a frame to a prescribed width, exposing only the horizontal rectangular strip in between, have also been provided. In these cameras, a transparent plate, such as a focusing screen, which indicates the exposure area in panorama mode with a frame is generally used; however, with this method, it is difficult to confirm the exposure area at the time of panorama photo-taking, and it is also difficult to know whether the camera is in full-size or panorama photo-taking mode.
In response to this situation, a camera is provided which contains a mechanism which changes the field from that for full-size photo-taking to a horizontally longer field for panorama photo-taking by placing darkening plates in the optical path in the vicinity of the focusing screen.
In a single lens reflex camera, it is desirable to apply a field frame changeover mechanism of a type which inserts darkening plates in order to provide accurate confirmation of the exposure area. However, in a single lens reflex camera, because the mirror which directs the light transmitted through the photo-taking lens to the viewfinder during framing is moved up to the vicinity of the focusing screen during shutter release, the movement of the mirror restricts the arrangement of the changeover mechanism, which could necessitate an increase in the size of the camera.